I ran them back in the 80's on my Sporty when Harley was selling them. I thought they rode way better than Dunlops, although as said, did not last quite as long. They seemed to be a softer rubber, and when you put on a new one, you could really tell a difference.
I run the Continental MT90H16 K112 on the front and rear, one of just a few tires that can be used for a front or rear tire depending on which way it's mounted on the rim. They used to say on the tire that they were made in Germany, but the last ones I got now say made in Korea, I don't see any difference though.
I think your lower mileage is due to that particular tire. The K112 an older design. I've been told the Conti Tour TK16/TK17 tires are what to go for if you're looking for higher mileage. They also make the Milestone CM1/CM2 tires for heavy tourers. I'd like to try a set to get some better mileage. The Texas roads eat my tires up during the summer heat.